Drying and splitting is quite possible. The mahogany cabin
sides on my boat cracked and split while the boat was covered and stored and I live in Washington
When I lived in New England
over 35 years ago, the old salts with wooden masts would insure their boats were moored on a buoy so the boats would turn in the sun. They believed that the sun on one side of the mast
would cause it to warp.
I have not seen many boats in AZ but the sun raised hell with wood when on boats I saw stored in Mexico
I don't think that mast
destruction is automatic in AZ however, but you are going to have to exercise some due diligence, to keep your varnish
up and your mast sealed.
I think a mast properly maintained will survive okay.
As for the effect on fiberglass
you should use white on the topsides, light color on the decks & cabin
, and a light colored bottom paint
. I had a black painted rudder
de-laminate in a boatyard when the sun baked it. Dark colored hulls get very hot as do teak
decks. Hulls topsides other than white fade as well and require frequent polishing and waxing. The fiberglass itself does not appear to be affected.